Honing is used to correct hole geometry and also to prepare surfaces that require a specific finish or scratch pattern. Typical of the latter are piston bores or liners in internal combustion engines. On such oil lubricated moving part surfaces it is customary to provide what is known as a plateau finish. A plateau finish is similar to a conventional finish, except that the peaks have been removed or flattened out. The finish attempts to duplicate the finish after the engine has been broken in, and removes or smooths out metal that would otherwise be removed by piston rings. A proper plateau finish contributes to the mechanical and environmental efficiency of the engine. This is usually accomplished by a two stage honing process including rough and finish honing.
Conventional honing tools are usually conventional stones or plated superabrasive tools. Most stones use vitrified, metal or resins bonds, and are similar to hard grinding wheels. Plated honing tools normally make use of super abrasives and consist usually of a single layer of abrasive attached to a metal surface by electrolytic plating. Inspection of the surfaces after use of these tools sometimes finds abrasive grains embedded in the metal surface, even though the honing operation is done under constant flushing with a lubricant or coolant. Abrasive contact with piston rings or other moving parts leads to premature wear, blow-by, or mechanical inefficiency, as well as environmental problems.
More recently, there has been developed a unique honing tool useful as a secondary or tertiary step honing tool which produces a superior honing finish in high production situations. An example of this type of tool is shown in Scheider et al U.S. Pat. No. 5,216,847, issued Jun. 8, 1993. A process for using the tool shown in such patent is disclosed in the copending application of Carmichael et al Ser. No. 07/941,544 filed Sep. 8, 1992, entitled "Honing Process" now U.S. Pat. No. 5,331,775.
There is also disclosed in the copending application of Tyler et al Ser. No. 08/052,366, filed Apr. 23, 1993, entitled "Honing Tool and Method of Making", a somewhat similar disposable honing tool for honing operations less exacting than high production operations.
The tool described in the above patents or copending applications comprises a bundle of tightly packed parallel monofilaments of relatively short extent, which bundle is secured in a holder. The holder is in turn mounted in the honing machine head and driven for rotation and reciprocation within the bore. The tightly packed tips of the monofilaments of the projecting bundle form the working face of the tool. The material of the monofilaments is nylon or other suitable fairly rigid and tough plastic, having the abrasive mineral or grain homogeneously entrained therein throughout. The monofilament may have as much as about 30 to about 45% by weight of abrasive material. The compacted tips provide a working face which has sufficient flexibility or softness to avoid planting abrasive in the work surface, and yet which is aggressive enough to form the proper surface and plateau finish. The compacted finger-like elements add stiffness and a degree of compliance to the tool. The compliance allows the tool to travel the surface and condition it even though it may have indentations and waviness.